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Date: December 16, 1993 Number of Pages (including cover page) Job No. 07549-001-141-05 I ky, = Z11111 Name: Ed Padilla Telecopy number called (209)464-0138 Firm• San Joaquin County - Public Health Services City• Stockton State: CA If you do not receive all of the pages, please call 091-(916)-939-4100 as soon as possible. From Name: Mark Urquhart Department Autoattendant No. 916-939-4139 Ext. 243 One of the items were discussed In our meeting on September 9, 1993 regarding design for the renovation of the Lovelace Road Transfer Station was grease/oil traps for storm drainage. There are four discharge points to the retention pond (See RSI -7). Three (DI's 16, 24, and 22) have peak flows of 13.7, 3.22 and 6.0 respectively. The fourth (Dl- 26) has only .63 cfs (from 2 Inlets only). As we discussed by telephone, I obtained information from P&L concrete regarding their typical sand and grease trap (attached). As with other typical grease traps, they are a modified septic tank with 4 inch lines. In view of the large pipe sizes and flows at Lovelace, use of this type of a separator may not be practical. The flows at Lovelace are too large to function with that type of unit (12, 24 and 30 inch lines). If these are installed on 24 and 30 inch lines it may likely result In the system backing up such that the inlets would flood. The typical grease traps appear to be designed more for lower flows associated with commercial kitchen waste or other lower flows. I have attached two details of grease traps that we have installed for storm water inlets on other jobs. They typically could be installed In a round (6' dia. may be needed) manhole to include an outlet pipe that is turned down 4 to 6 inches below the level of the inlet. A baffle plate could be Installed for units which also function as an inlet. A customized inlet/manhole similar to these could be installed on each branch at key locations to serve as a separator (DI's 16, 22, 24 and 26). These would Include a unit on each branch at inlets just prior to pond discharge. The retention pond could also be routinely cleaned to remove sift. Note also that the truck wash and transfer' tunnel will have dedicated traditional grease/grit separators. The transfer tunnel will have a separator installed upstream of a lift pump which would discharge to a holding tank. The truck wash separator will be pan of a recirculating wash water system. I have discussed this with Gabriel Karam. Please contact me to discuss this so we can finalize plans. Thanks. cc: Gabriel Karam, S.J. County, Public Works d:\mju\fts\lea2